Bernd, You are remarkable! I would love to use your library! Thinking of moving to Brighton? :-)
----- Original Message ----- From: "Bernd Pauli HD" <[EMAIL PROTECTED]> To: "Dave Harris" <[EMAIL PROTECTED]> Cc: "metlist" <[EMAIL PROTECTED]> Sent: Monday, January 07, 2002 8:40 PM Subject: Breccia formation > Dave Harris wrote: > > > So, can I assume that the meteorite, prior to ejection from the parent > > asteroid was already a brecciated rock lying on the surface or embedded in > > the lithosphere, or does brecciation occur when the regolith is pounded by > > an impact, fusing together all the different rocks lying around on the > > surface of the planetoid? > > Hello again, > > J�CKEL A. et al. (1998) Textural and mineralogical differences > between LL-chondritic fragmental and regolith breccias > (Meteoritics 33-4, 1998, A077, excerpts): > > "Essentially, two different types of breccias can be distinguished: > regolith breccias and the more abundant fragmental breccias. Regolith > breccias derive from the uppermost surface material of the parent > bodies, and contain significant concentrations of solar-wind-implanted > noble gases as well as preirradiated mineral grains. Fragmental breccias > represent material that was shielded from irradiation, and do not > contain solar-wind-implanted noble gases." > > "The chemical compositions of the matrix olivines in regolith breccias > vary, unlike the composition of matrix olivines in fragmental breccias. > The occurrence of clasts showing different olivine compositions > indicates that equilibrated and unequilibrated lithologies were mixed > together by impact events after the equilibrated and recrystallized > fragments were formed by thermal metamorphism." > > > Best wishes, > > Bernd ______________________________________________ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
